Solve the system of equations. $\begin{aligned} & -5x+2y = 9 \\\\ & y=7x \end{aligned}$ $ x=$
Explanation: We are given that $ y = {7x}$. Let's substitute this expression into the first equation and solve for $x$ as follows: $\begin{aligned} -5x+2{y}&=9\\\\ -5x+2\cdot{7x}&=9\\\\ -5x+14x& = 9\\\\ 9x&=9\\\\ x&=1 \end{aligned}$ Since we now know that $ x={1}$, we can substitute this value into the second equation to solve for $y$ as follows: $\begin{aligned} y &= 7{x} \\\\ y&=7\cdot{1}\\\\ y&=7 \end{aligned}$ This is the solution of the system: $\begin{aligned} &x = 1 \\\\ &y=7 \end{aligned}$